Numerous documents describe such tyres comprising a self-sealing layer on all or part of their interior surface.
By way of example, document U.S. Pat. No. 4,418,093 describes a method for evenly applying a layer of self-sealing material to the interior wall of a vulcanized tyre by combining a rotation of the tyre followed by oscillatory movements until the self-sealing material is sufficiently crosslinked that it no longer flows.
When the self-sealing layer is applied to the uncured green form of a tyre, one of the problems encountered is due to the highly tacky nature of the self-sealing layer which adheres strongly to the curing membrane during the vulcanizing phase. After the vulcanized tyre leaves the curing mould, bits of the self-sealing layer may remain stuck to the wall of the membrane and thus cause it soon to be scrapped. During this high-temperature vulcanizing phase, ingredients of the self-sealing layer may also migrate into the curing membrane and this may likewise reduce the life thereof. The anti-tack agents conventionally used, such as whitewashes or silicone-containing liquids, are entirely inadequate for solving this problem.
To solve this problem, document U.S. Pat. No. 4,664,168 discloses a tyre with a self-sealing layer incorporated at the time of manufacture of the tyre. This tyre is comprised of an external rubber tread, a carcass reinforcer, a gastight layer arranged on the inside relative to the carcass reinforcer and an anti-tack layer arranged furthest towards the inside. It also is comprised of a self-sealing layer adjacent to the anti-tack layer and arranged on the inside relative to the gastight layer. The anti-tack layer consists of a powder such as talc or zinc stearate.
The anti-tack layer makes the tyre easier to manufacture by limiting direct contact between the self-sealing layer and the tools used for building the green tyre. However, when vulcanizing a green tyre in a mould that has a curing membrane, the extending of the green tyre as a result of the pressure applied by the curing membrane causes the particles to move further apart and leads to the possibility of the self-sealing product coming into direct contact with the curing membrane.